How Personality Tests Work

Many websites offer free personality tests. These are some of the questions in an online test called 16 Personalities. www.16personalities.com

There are also concerns regarding how personality tests are used in the real world. Responding to worries that MBTI results are used to hire, fire or promote employees, Segovia said, "The MBTI tool is used to develop employees and to bring out the best performance by helping them become more self-aware, and also more aware of the differences in preferences and talents that other people bring to the table. However, it is not designed for, nor should it be used for any kind of selection (hiring, promotions, etc.)." Yet, up to 60 percent of workers are asked to take workplace tests, and many organizations even give personality assessments to job candidates [source: Meinert].

The CPP does portray the MBTI categories in a positive light — Segovia even referred to the test as a forerunner of positive psychology. All 16 types are considered equal, but some may excel at particular types of work or engage with specific personality types better. But one slightly negative perspective we found when taking the MBTI was a discussion of what might happen if a type takes a preference too far, possibly because of stress. For instance, there are many positive aspects of being an INTP, but if you're too INTP, you might be guilty of "overintellectualizing and becoming too theoretical in your explanations," as the MBTI puts it.

Regarding the validity and repeatability of the results (Jung, Myers and Briggs contended that a personality type was something you have for life), Segovia told us that different results in retakes of the assessment simply suggest that the initial response was close to the center line in the dichotomy, so a few different answers would push a person to the other side of the dichotomy. This could be easily interpreted as pointing out a major flaw in any effort to divide people into rigid categories, however — if an assessment has repeatable results, changing a small number of answers shouldn't drastically affect the outcome. Regardless, Segovia said in an email, "Test and re-test agreement for each aspect of MBTI type is nine times higher than chance, and for three of the four dimensions it is about three times higher than chance, meaning that individuals are likely to receive the same results on consecutive MBTI administrations."

So, the scientific value of personality tests is under much scrutiny, thanks to their wavering legitimacy and the ambiguity of personality itself. But personality testing is used widely, in counseling, employment, therapy and elsewhere. Despite the criticism leveled against these tests, they remain successful — and profitable.